The Policeman’s Benevolent Association, which represents most Port Authority of New York and New Jersey police officers announced the endorsement Tuesday. The union had backed Christie’s rival, incumbent Democratic Gov. Jon Corzine, four years ago.

“Four years ago I stood on this podium with a different message,” PBA president Paul Nunziato announced Tuesday at the Newark Airport Hilton. “Our state and nation were in crisis and we needed a new direction. Our governor has provided us with a new direction.”

Nunziato said that while Corzine treated the union fairly, Christie has treated them “tremendously.” He cited the governor’s backing of Port Authority police in their dispute with the New York City police department over who will provide security at the redeveloped World Trade Center site.

Christie drew the largest of several standing ovations during his remarks when he touched on the issue.

“Never, not ever, on my watch will there be any other police force who will patrol the new World Trade Center,” he said.

Port Authority police patrol the New York metropolitan region’s airports, tunnels, bridges and ports in addition to the World Trade Center site.

Christie’s approval ratings have soared since superstorm Sandy hit the state and he became a national symbol of New Jersey’s pluck and determination as he visited hard-hit areas. He later chastised his own party’s representatives in Washington for taking several weeks to approve an aid package.